Leaks Only When Cold Outside

Saddle horse · February 18, 2015

2002 Silverado 1500 Z71 with a 5.3 and auto .

Water pump leaks bad but only when below 50deg out . Been doin it for 2 years now .

Replaced all the gaskets and still does it wen below 50deg .

Why would it only leak in cold weather ?

Cowpie · February 18, 2015

Metal, like most other things, contracts when cold, expands when hot. There could also be a very small crack in the pump itself, that only allows coolant out when the pump is cold. I have had this very same thing happen time and time again on my commercial semi trucks and other equipment. Every time, only a total pump replacement cured the issue.

Saddle horse · February 18, 2015

I thought about that myself , but what got me is after the truck warms up and drive all day long it still does it .

So wouldn't it stop when the motor is being ran all day an warmed up ? No matter what it won't stop still the outside temp is above 50deg .

When driving the engine and water pump temp is way over that . That is why I can't figure it out .

Thanks

sahls01gmc · February 18, 2015

I'd replace the pump and gaskets. Make sure all surfaces are 100% clean. Mine leaked like yours did, and after replacement it has been leak free!

Saddle horse · February 18, 2015

When I had the pump off cleaning and replacing the gaskets I couldn't find any cracks or anything . Also only leaks when engine isn't running .

sahls01gmc · February 18, 2015

I would still replace it. How are the hoses? How bout the thermostat?

Saddle horse · February 18, 2015

Hoses and thermostat are new , the water pump is less than a year old as well . Had it in the shop last year under warranty and they replaced the pump.

I done new gaskets back at first of winter cause it started again when it got cold out .

Guess could be a bad GM pump

sahls01gmc · February 18, 2015

Hmm, possible. I've had some bad luck with replacement parts in the past. Wouldn't be surprised that a cheap $75 pump is faulty. Was it a reman, or new?